Dielectric ceramic compositions for various electronic devices, which make use of better temperature characteristics with lower loss of the properties of the ceramic composition, include a variety of dielectric ceramic compositions which are used in microwave strip line substrates and dielectric resonators such as for down convertors and satellite communications utilizing the lower loss of properties at the SHF bands, including temperature compensation capacitors.
Complex perovskite compounds of Ba(B.sub.1/3.A.sub.2/3)O.sub.3 compositions (A: Ta, and B: divalent metal ions (Zn and/or one or more of Ni, Co, and Mn)) are widely used in particular among conventional perovskite compounds as dielectric ceramic compositions generally employed in SHF bands.
The properties required of Ba(Zn.sub.1/3.Ta.sub.2/3)O.sub.3 compositions used in the SHF bands, such as a higher .di-elect cons.r, a high Q, and .tau.f=0, are particularly stringent. The composition must be controlled to be meet such properties, and must therefore be sintered for long periods of times, such as for about 100 hours at 1500.degree. C.
It is important to control the composition, particularly the Zn content, which tends to volatilize, in conventional dielectric ceramic compositions. Zn also diffuses or spreads to the outside of the ceramic during sintering, resulting in Zn-deficient components such as Ba.sub.5 Ta.sub.4 O.sub.15, which tend to form what is referred to as "skin," making it difficult to consistently obtain a ceramic with internal homogeneity, as well as to obtain a ceramic with stable properties.
There is a particular need to adjust the resonance frequency temperature coefficient .tau.f to a specific level according the application. Ba(Zn.sub.1/3.Ta.sub.2/3)O.sub.3 is known to have a .tau.f of around 0.
Research on the aforementioned Ba(Zn.sub.1/3.Ta.sub.2/3)O.sub.3 composition in order to control the Zn content in dielectric ceramic compositions with complex perovskite compounds has resulted in the proposal of a Ba(Zn.sub.1/3.Ta.sub.2/3)O.sub.3 --YSr(Ga.sub.1/2. Ta.sub.1/2)O.sub.3 solid solution system containing specific trivalent metal ions and an XBa(Zn.sub.1/3.Ta.sub.2/3) O.sub.3 --Y(Ba.sub.Z.Sr.sub.1-Z)(Ga.sub.1/2.Ta.sub.1/2)O.sub.3 solid solution system (Japanese Laid-Open Patent Application (KOKAI) 2-285616 and Japanese Laid-Open PCT Patent Application (KOHYO) 7-102991).
The recent shifts to smaller electronic devices for communications systems and higher frequency bands in the communications field have resulted in the need for greater dielectric elements because of the lower dielectric constant in conventional dielectric ceramic compositions.